This proposal involves the study of NADPH-cytochrome c (P-450) reductase in various organs from both experimental animals and human tissue obtained at autopsy. The following experimental goals have been set for the coming year: 1) Studies on NADPH-cytochrome c (P-450) reductase isolated from liver, kidney, and lung tissue with respect to physical properties for comparative purposes; 2) reconstitution of mixed-function oxidase systems from the various organs utilizing the purified reductase and cytochrome(s) P-450 isolated from these tissues in an effort to understand the specificities of these activities and the mode of interaction between reductase and cytochrome P-450; 3) continuation and extension of ongoing experiments with heme oxygenase activities catalyzed by liver and spleen microsomes; 4) extension of the experiments on membrane-bound NADPH-cytochrome c (P-450) reductase using stopped-flow and EPR techniques; 5) and the continuation, when feasible, of tissue localization studies using light and electron microscopic techniques with antibody-labelled microsomal constituents. BIBLIOGRAPHIC REFERENCES: Characterization of NADPH-Cytochrome c (P-450) Reductase Purified by Biospecific Affinity Chromatography Utilizing Spectrophotometric and Electron Paramagnetic Resonance Techniques, Y. Yasukochi, J.A. Peterson, and B.S.S. Masters, in Microsomes and Drug Oxidations, 3rd International Symposium (A.H. Conney, R.W. Estabrook, A.G. Hildebrandt, and V. Ullrich, Eds.), Pergamon Press, Oxford, England, in press (1977). Omega- and omega-1 Hydroxylation of Fatty Acids by Mixed-Function Oxidase Systems, B.S.S. Masters, R.T. Okita, L.L. Fan, R.A. Prough, for Methods in Enzymology, Biomembranes, Cells, Organelles, and Membranous Components, S. Fleischer, L. Packer, and R.W. Estabrook, Eds.), Academic Press, in press (1977).